FIG. 1 is a perspective view of a rack base plate showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is another perspective view thereof;
FIG. 9 is a rear elevational view of the design in a state of use; and,
FIG. 10 is an enlarged sectional view taken along line 10-10 of FIG. 9.
The broken lines shown in FIGS. 9 and 10 are for illustrating environment only and form no part of the claimed design.